Tissue marking implant

ABSTRACT

A tissue marking implant includes a matrix material and a dye marker. The implant, which can be formed entirely of bioresorbable material such as a collagen foam, is sized and shaped to replace excised tissue. The implant supports surrounding tissue upon implantation, while allowing for in-growth of fibrous tissue to replace the implant. According to various alternative embodiments, the implant is elastically compressible, or can be formed from self-expanding foam or sponges, and can be implanted through a cannula or by injection, as well as by open procedures. The implant can carry therapeutic and diagnostic substances. The dye marker leaches from the implant such that a surgeon, upon subsequent surgical intervention, visibly recognizes the tissue marked by the dye marker.

This application is a continuation in part of U.S. patent applicationSer. No. 10/627,718, filed Jul. 28, 2003, now U.S. Pat. No. 6,881,226,which is a continuation of U.S. patent application Ser. No. 09/828,806filed Apr. 10, 2001, now U.S. Pat. No. 6,638,308, which is a division ofU.S. patent application Ser. No. 09/169,351, filed Oct. 9, 1998, nowU.S. Pat. No. 6,214,045, which claims the benefit of U.S. ProvisionalApplication Ser. No. 60/061,588, filed Oct. 10, 1997, U.S. ProvisionalApplication Ser. No. 60/077,639, filed Mar. 11, 1998, and U.S.Provisional Application Ser. No. 60/091,306, filed Jun. 30, 1998, thedisclosure of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to implantable prostheses. Moreparticularly, the present invention relates to implantable breastprostheses designed to eliminate encapsulation and reduce scarring, andto replace tissue removed for purposes of biopsy or lumpectomy.

DESCRIPTION OF THE RELATED ART

Breast prostheses are utilized for augmentation mammoplasty and incosmetic surgery. Prostheses are also indicated in breast cancersurgery, such as lumpectomies, where a portion of the breast is removedand can leave some disfigurement if not replaced by a similar amount oftissue and/or augmentation material.

Similarly, biopsies can leave small dimples or imperfections if remedialsteps are not taken. About 1 million breast biopsies are performed inthe United States annually. As a result, some 200,000 new breast cancersare diagnosed each year.

Known methods of augmentation mammoplasty utilize silicone or salineimplants. These methods have been complicated post-operatively byencapsulation of the implants, which can occur to varying degrees.Encapsulation produces a hard area of scar tissue around the implant,resulting in a rigid, abnormally-shaped mount beneath the breast tissueor pectoralis muscle, depending upon the placement of the implant.

Moreover, the known implant materials may not be indicated forreplacement of smaller amounts of tissue, as would be required toprevent dimpling after biopsies, for example. Further, the known implantmaterials are not amenable to resizing. In addition, known implants arenot capable of being implanted through a cannula or needle, and are notreadily instilled with medicaments or chemical agents that would beuseful in treating the patient.

Accordingly, a need exists for implants and methods that can be adaptedfor replacement of small as well as large amounts of tissue. A need alsoexists for implants that can be delivered through cannulae or needles,as well as being able to significantly reduce or eliminateencapsulation, resulting in a prolonged, aesthetically pleasing, softmound below the breast tissue or pectoralis muscle. In addition, a needexists for implants into which useful substances, such as beneficialmedications, chemical agents, hormonal treatments, stem cells, such asadipocytes, cellular precursors and components, and radiation media canbe instilled to enhance the treatment capabilities of the implant incancer and other breast pathology.

BRIEF SUMMARY OF THE INVENTION

The present invention overcomes deficiency of the prior art, such asthose noted above, by providing an implant in which at least the outerportion of the implant, and as much as the entire implant, is made of aresorbable material. The implant is sized and shaped to reduce excisedtissue. Preferably, the implant provides a support structure in the formof a framework or scaffold for the surrounding tissue afterimplantation. The support structure preferably is porous to permit thein-growth of fibrous replacement tissue. Advantageously, replacementtissue in-growth takes place without encapsulation and with reducedscarring.

According to an embodiment of the invention, excised tissue is replacedby installing an implant having at least an outer shell of resorbablematerial. The implant is sized and shaped to replace the excised tissue.The implant supports surrounding tissue while fibrous tissue replacesthe resorbable portion of the implant.

In a further development, at least a portion of the implant can beprovided in the form of a compressible or non-compressible sponge orfoam, or a self-expanding sponge or foam. The sponge or foam provides aporous support matrix for surrounding and in-growing tissue. In the formof a compressible, expandable, or self-expanding sponge or foam, theimplant advantageously can be inserted through a cannula or a needle, oroptionally can be directly inserted. Additionally, the implant can beinstilled with beneficial materials, such as indicated medicaments,therapeutics, or diagnostic agents, as well as matrix enhancingadditives.

Other features and advantages of the present invention will becomeapparent from the following description of the invention which refers tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic elevation of a breast implant according to apreferred embodiment of the present invention.

FIG. 2 is a schematic sectional view of a breast after implantation ofthe implant of FIG. 1.

FIG. 3 is a schematic sectional view of a breast after implantation ofan alternative embodiment of the implant of the present invention.

FIG. 4 is a schematic sectional view of a breast implant according to asecond alternative embodiment of the present invention.

FIG. 5 is a schematic sectional view of a breast after implementation ofthe implant of FIG. 4.

FIG. 6 is a schematic sectional view of a breast implant and a method ofinsertion according to further alternative embodiments of the presentinvention, particularly for cases involving the removal of smallerpieces of tissue such as by biopsy and lumpectomy.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to FIGS. 1 and 2, an implant 2 has an outer shell 4made of a biosorbable material woven into a mesh. The inner contents ofthe implant are fluids such as saline and autologous blood products.

Outer shell 4 is made entirely of biosorbable materials, such ascollagens or polyglycolic acids, for example. Over a period ofapproximately three weeks to six months, the outer shell dissolves,leaving the inner contents 6 present inside the breast. Hardencapsulation will not occur because there is not a foreign bodycontained within the prosthetic space.

Referring to FIG. 3, implantation of an alternative embodiment ofimplant 2 is illustrated in which the outer shell 4 includes bothbiosorbable material, and non-absorbable material, such as monofilamentpolypropylene fibers. Outer shell 4 is provided as a mesh or weave ofthe mixed material, surrounding contents 6 as described above. After aresorption period, contents 6 remain surrounded by a skeletal outershell made up of non-absorbable fibers 8.

Advantageously, the proportions and spacing of the two types ofmaterials can be altered to provide the desired properties ofcontainment using a minimal amount of nonabsorbable material.Accordingly, the non-absorbable fibers 8 which remain after thebiosorbable materials resorb will act as a scaffolding to allow theprosthesis to hold its shape; however, because of the limited amount offoreign material, encapsulation and scarring are decreased.

Referring to FIGS. 4 and 5, a second alternative embodiment of thepresent invention is shown. A prosthesis 10 features two capsules, alarger, outer capsule 12 made of biosorbable materials, and a smallerinner capsule 14 made of a non-absorbable material. Inner capsule 14also can be made partially resorbable as in the first alternativeembodiment above. Outer capsule 12 and inner capsule 14 can be separatedby a thin layer 16 of saline or autologous fluids such as thosedescribed above. Inner capsule 14 surrounds a more permanent member 18made of autologous fluids or saline, for example.

After implantation, outer capsule 12 dissolves, thus preventinghardening by encapsulation of the prosthesis. The supply of fluid 16between the capsules (a few to several c.c.'s) is absorbed by the bodyonce released by the dissolution of outer capsule 12.

Referring to FIG. 6, a further alternative embodiment of the presentinvention includes an implant prosthesis 20 provided in the form of amatrix framework, such as a sponge or foam. The implant, whichpreferably is entirely biodegradable (resorbable), has a porousstructure which supports the surrounding tissue and provides a frameworkfor the in-growth of fibrous tissue material. FIG. 6 illustrates tissueportion 24 surrounding implant 20 into which marker dye included in theimplant, and described further below, has leached over time from theimplant, thereby marking the tissue. Accordingly, a surgeon performing asubsequent procedure easily will recognize the tissue surrounding theprevious excision.

According to a preferred embodiment, the implant is provided in the formof a foam or sponge which can be modified by a surgeon prior toimplantation, such as at a lumpectomy or biopsy site, simply by trimmingthe sponge to the appropriate size and shape. Alternatively, the implantcan be a pre-shaped prosthesis of appropriate size, or an appropriateamount of foam or foam-forming materials. Optionally, the foam can beprovided as a self-expanding matrix that either is compressed, or formsin situ. Advantageously, the implant can be modified to correspond tothe breast tissue that either has been removed, requires replacement, orrequires augmentation. The foam or sponge matrix is sufficientlyresilient to support the surrounding tissue without collapsing.

A preferred embodiment of implantation is illustrated schematically inFIG. 6, whereby the implant is elastically compressible, and isdelivered using a cannula or needle 22 inserted into the breast. Asingle implant 20 is shown being compressed so as to fit within cannula22. A force is applied to drive the compressed implant distally throughand out the distal end of the cannula into the implant site, where theresilient implant 20 expands to fill the implant site space.

The force for advancing the sponge or foam material through the cannulacan be applied directly to the implant, or indirectly using fluids, forexample. Advantageously, the implant can be used in conjunction withstereotactic biopsy instrumentation, such as the ABBI® System, the MIBSystem by US Surgical, or the Mammotome® System by Johnson and Johnson.

As a further alternative, the sponge or foam implant of the presentinvention can form all or part of a larger implant, such as thosedescribed above. Accordingly, the tissue supporting sponge or foam orfoam matrix will form, for example, all or part of the outer shell 4 ofimplant 2. Implantation using open procedures usually would be indicatedwhen the sponge implant of the present invention is used as all or partof a larger implant. Accordingly, the sponge or implant would be placeddirectly into the biopsy or lumpectomy cavity.

In addition, the implant 20 can be provided in the form of aself-expanding foam, which can be injected through a tubular member 22such as a needle or cannula in a metered amount. An appropriate amountof foam-forming materials can be inserted through cannula 22 and allowedto expand or form a matrix within the cavity created by the excisedtissue. Alternatively, a specialized, applicator may be used to injectthe desired amount of the foam. The amount of foam is preselected toallow sufficient expansion to fill the void left by the excision andsupport the surrounding tissue to prevent dimpling.

Following insertion of the implant, such as by an open method or one ofthe stereotactic methods described above, the resorbable implantoccupies the breast tissue cavity and supports the surrounding tissueuntil such time as it resorbs or biodegrades. After initialimplantation, the patient's own fluids, fibroblast, and stem cells, suchadipocytes, vascular stem cells, and others, permeates the spongeprosthesis. In the case of a small implant, such permeation would occurnaturally, subsequent to implantation. In the case of a larger implant,providing the implant at least partially filled with fluids prior toimplantation may be indicated.

Advantageously, the new prosthesis decreases encapsulation afterimplantation. Various biosorbable materials can be used in the implantof the present invention. Known biosorbable materials includepolyglycolic acid (Dexon, Davis & Geck); polyglactin material (Vicryl,Ethicon); poliglecaprone (Monocryl, Ethicon); and synthetic absorbablelactomer 9-1 (Polysorb, United States Surgical Corporation).

Other foamable materials that can be utilized in the present inventioninclude, without limitation, proteins such as collagen, fibronectin,laminin and fibrin, most preferably collagen, and high molecular weightpolysaccharides, such as heparan sulphate, chondroitin sulphate,hyaluronic acid and dermatan sulphate. Mixtures of any of theaforementioned materials also can be used, as required.

The materials can be modified, by cross-linking for example, to controldegradation rates over varying lengths of time, after which they aresubstantially or completely resorbed.

Foams can be formed by various means known to those skilled in the art,including injecting an aerosol into a gel, and freeze-drying aqueousdispersions of the foam-forming material. Foaming agents can be includedto promote formation of the foam. In addition, stabilizing agents can beincluded to enhance foam stability. The foams can be extruded or formedin situ.

According to the present invention, these products may be mixed with oneanother or combined to provide various resorption times or gradients,and/or may be interrelated with non-absorbable materials, such aspolypropylene or PTFE (polytetrafluoroethylene) sold as (Gore-Tex®)material, for example. In an instance where a non-absorbable material isutilized, the non-resorbable implant section will remain partiallyintact as a permanent structure.

In each of the embodiment, the resorbable portions of the prosthesisultimately biodegrades, and the patient is left with autologous tissue,some of which may have been implanted, or a permanent implant such assaline, as a filler for the biopsy cavity, thus preserving the contourof the breast and preventing indentation of the overlying skin.

The implants of the present invention further can be instilled, beforeor after implantation, with indicated medicines and other chemical ordiagnostic agents. Examples of such agents include, but are not limitedto, antibiotics, chemotherapies, other cancer therapies,brachytherapeutic material for local radiation effect, x-ray opaque ormetallic material for identification of the area, hemostatic materialfor control of bleeding, growth factor hormones, immune system factors,gene therapies, biochemical indicators or vectors, and other types oftherapeutic or diagnostic materials which may enhance the treatment ofthe patient.

The breast implant preferably includes a permanent or temporary dyemarker such as, but not limited to, indigo carmine or methylene blue.This marker serves as a visual identification of the area that has beenbiopsied or a lumpectomy has been performed so that in the future anoperating surgeon can identify the surrounding tissue before he violatesthe previously biopsied cavity. These dyes leach into the breast tissuegiving the surgeon an indication when he is nearing the point ofinterest, that being a previous biopsy site particularly if it ispositive for a cancer or if it is a site for which a lumpectomy has beenpreviously performed and the pathologist advises us that there isresidual cancer. The surgeon can thus remove any of the surroundingbreast tissue that contains dye and depending upon its concentration andthe distance that it has traveled from the biopsy site will give us anindication of how much tissue should appropriately be removed.

This dye may be integrated with a bioabsorbable material such as, butnot limited to collagen or may be in a separate capsule that is insertedwith the bioabsorbable material as well as a metallic device forradiographic identification.

These two dyes are very dark colored dyes and these do leach through thebreast tissue but will not stain the overlying skin.

The present invention has been described particularly in connection witha breast implant, but it will be obvious to those of skill in the artthat the invention can have application to other parts of the body, suchas the face, and generally to other soft tissue or bone. Accordingly,the invention is applicable to replacing missing or damaged soft tissue,structural tissue or bone, or for cosmetic tissue or bone replacement.

Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not only bythe specific disclosure herein, but only by the appended claims.

1. An implant system for filling a cavity formed by removal of softtissue from a site within a patient's breast comprising: an elongateddelivery cannula having a proximal and a distal end and an inner lumenextending therein; a compressed resilient implant disposed within theinner lumen of the delivery catheter and formed of foamed or spongematrix material which is at least in part bioabsorbable and which has amarking material, the implant being formed to fit the cavity in thepatient's breast, and configured to support tissue surrounding thecavity when delivered thereto and expanded therein and to allowin-growth of fibrous tissue into and replacing at least a portion of thefoamed or sponge matrix material.
 2. The implant system of claim 1,wherein the marking material is a dye.
 3. The implant system of claim 2,wherein the dye is one of indigo carmine and methylene blue.
 4. Theimplant system of claim 1, wherein the matrix material is elasticallycompressible.
 5. The implant system of claim 1, wherein the matrixmaterial is formed of a foamed bioabsorbable protein.
 6. The implantsystem of claim 1, wherein the matrix material is formed of a foamedcollagen.
 7. The implant system of claim 1, wherein the matrix containsat least one medicinal, therapeutic, or diagnostic substance.
 8. Theimplant system of claim 7, wherein the at least one substance isselected from the group consisting of radiation materials, antibiotics,chemotherapies, cancer therapeutics, hemostatic materials, hormonetherapeutics, and radiographic markers.
 9. The implant system of claim1, wherein the implant has a shell containing the matrix material. 10.The implant system of claim 9, wherein the shell comprises compressedmatrix material.
 11. The implant system of claim 9, wherein the shellcompletely surrounds the matrix material.
 12. The implant system ofclaim 1 wherein the marker material is a radiographic element.
 13. Theimplant system of claim 12 wherein the radiographic element is formed ofa metallic material.
 14. A tissue marking implant system for filling acavity formed by removal of soft tissue from a site within a patient'sbreast comprising: an elongated delivery cannula having a proximal and adistal end and an inner lumen extending therein; an expandable matrix ofcollagen material compressed within the inner lumen of the deliverycannula, the matrix having a porous structure configured for supportingtissue surrounding the cavity formed in the patient's breast andconfigured to provide a framework for the in-growth of fibrous tissueinto the matrix when deployed from the distal end of the deliverycannula and disposed within the cavity formed in the patient's breast;and a dye marker supported by the matrix for dispersion within thecavity.
 15. The tissue implant of claim 14, wherein the porous structureof the matrix comprises a foam.
 16. The tissue implant of claim 14,wherein the porous structure of the matrix comprises a resilientframework which expands resiliently within the cavity in the patient'sbreast to support tissue surrounding the cavity.
 17. The tissue implantof claim 14, wherein the porous structure of the matrix isself-expanding within the patient's breast.